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Near-infrared imaging observations of the southern massive star-forming region G333.6-0.2
We present near-infrared broad-band JHK' images of the southern massivestar-forming region G333.6-0.2. The slope of the K-luminosity functiontowards the region (0.24 +/- 0.01) is considered to be equivalent tothat expected for main-sequence stars in the solar neighbourhood. Pointsources with their (H-K) colour greater than 1 are more likely to belocated in extended emission and it is suggested that these objects arephysically associated with the HII region.
| The cluster environments of radio-loud quasars at 0.6 < z < 1.1
We have carried out multicolour imaging of a complete sample ofradio-loud quasars at 0.6 < z < 1.1 and find groups or clusters ofgalaxies in the fields of at least eight and possibly 13 of the 21sources. There is no evidence for an evolution in the richness of theenvironments of radio-loud quasars from other low-redshift studies toz>~ 0.9. The quasars associated with groups and clusters in oursample do not necessarily reside in the centre of the galaxydistribution, which rarely displays a spherical geometry. Clustering ispreferentially associated with small or asymmetric steep-spectrum radiosources. The quasars with the largest projected angular size are, innearly all cases, found in non-clustered environments. Radio-basedselection (including source size) of high-redshift groups and clusterscan be a very efficient method of detecting rich environments at theseredshifts.We find that in optical searches for galaxy overdensities above z~ 0.6,multiple filters must be used. If the single-filter counting statisticsused by groups at lower redshift are applied to our data, uncertaintiesare too large to make accurate quantifications of cluster richness. Thismeans that genuine clustering of galaxies about quasars will be missedand, in ~10 per cent of cases, putative clusters turn out to be falsedetections. The statistics are further diluted by the fact that galaxyoverdensities are generally not centred on the quasar.
| JHK Standard Stars on the CIT Photometric System
We present a set of 58 stars with JHK standard values on the CIT systemand with a suitable magnitude range for use with array detectors onsmall- to moderate-size telescopes. Each final value is based on six to47 measures (with a mean of 17) obtained on separate nights with the USNaval Observatory (USNO) NICMOS3 (HgCdTe) camera. The objects include 20primary CIT standards from Elias et al. and 38 secondary sourcesselected from the SAAO and UKIRT standards lists, cover a K-magnituderange between 6.0 and 10.8, and lie north of declination -20°. Thestars were reduced to the CIT system as defined by Elias et al.,producing a USNO system that is identical to the near-infrared CITsystem. This work densifies the original CIT system by nearly a factorof 3 and extends its range by about 3 mag. The SAAO and UKIRT standardsare also compared with the CIT system.
| Fainter Southern JHK Standards Suitable for Infrared Arrays
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995MNRAS.276..734C&db_key=AST
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Dades d'Observació i Astrometria
| Constel·lació: | Ophiucus |
| Ascensió Recta: | 16h24m26.00s |
| Declinació: | -17°44'42.9" |
| Magnitud Aparent: | 9.653 |
| Moviment propi RA: | -1 |
| Moviment propi Dec: | -7.4 |
| B-T magnitude: | 10.292 |
| V-T magnitude: | 9.706 |
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